Webhook v3

What's Changed

• Updated README to remove version and extra . by @pavelgj in #2
• Webhooks V3 by @El-Fitz in #4
• Hotfix/extension name and extension update instructions by @El-Fitz in #5

New Contributors

• @pavelgj made their first contribution in #2

Full Changelog: https://github.com/Purchasely/Purchasely-Firebase-Extension/commits/1.0.2